#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    int p,n=-1;
    ifstream be("fact.in");
    be>>p;
    be.close();
    if (p%6==0)
        n=p*5-p/6*5;
    else
        if ((p+1)%6==0)
            n=-1;
        else
            n=p*5+p/6*5-10*p/6;
    ofstream ki("fact.out");
    ki<<n;
    ki.close();
    return 0;
}